Package take-up control for stuffer box crimpers

ABSTRACT

A stuffer box crimping machine includes feed means for supplying yarn to a stuffer box to form a plug of yarn therein, a detector means arranged to produce a level-dependent electrical output in dependence on the level of the plug of yarn in the stuffer box a diameter sensor to produce a diameter dependent electrical output in dependence on the package into which the yarn is formed, and a speed sensor to produce a feed-dependent electrical output in dependence on the rate of supply of yarn by the feed means to the stuffer box. The yarn is withdrawn from the stuffer box by a take-up device driven by a D.C. motor, and control means are arranged to receive the level-dependent electrical output; the diameter dependent electrical output, and the feed dependent electrical output. to thereby control the rotational speed of the D.C. motor so that the plug of yarn in the stuffer box is maintained between pre-determined limits in dependence on the electrical outputs.

United States Patent 1191 Cartlidge et al.

[ 1 PACKAGE TAKE-UP CONTROL FOR STUFFER BOX CRIMPERS [75] Inventors: Albert Joseph Cartlidge; Frank Shuttleworth, both of Bolton, England [73] Assignee: Platt International Limited,

Lancashire, England [22] Filed: Jan. 30, 1973 [21] Appl. No.: 327,923

[30] Foreign Application Priority Data [451 Feb. 4, 1975 Primary ExaminerRobert R. Mackey Attorney, Agent, or Firm-Watson, Cole, Grindle & Watson [57] ABSTRACT A stuffer box crimping machine includes feed means for supplying yarn to a stuffer box to form a plug of yarn therein, a detector means arranged to produce a level-dependent electrical output in dependence on the level of the plug of yarn in the stuffer box a diameter sensor to produce a diameter dependent electrical output in dependence on the package into which the yarnis formed, and a speed sensor to produce a feeddependent electrical output in dependence on the rate of supply of yarn by the feed means to the stuffer box. The yarn is withdrawn from the stuffer box by a takeup device driven by a D'.C. motor, and control means are arranged to receive the level-dependent electrical output; the diameter dependent electrical output, and the feed dependent electrical output. to thereby control the rotational speed of the DC. motor so that the plug of yarn in the stuffer box is maintained between pre-determined limits in dependence on the electrical outputs.

5 Claims, 2 Drawing Figures PATENTEU FEB H975 SHEET 1 OF 2 PATENTED FEB W SHEET 2 OF 2 1 PACKAGE TAKE-UP CONTROL FOR STUFFER BOX CRIMPERS The invention relates to textile'machines used for stuffer box crimping of yarns, and to a method of controlling such machines.

ln textile machines used for stuffer box crimping of yarns, yarn is fed by a yarn feed assembly to a stuffer box to form a plug of yarn therein, and the crimped yarn is withdrawn from the stuffer box by a yarn take up device. A hitherto proposed machine of this type employs a single constant speed electric motor which drives, via one or more variable speed drives, the yarn feed assembly, the crimping wheels of the stuffer box, and the yarn take-up device. The speed of the yarn take up device is controlled in dependence on the level of the plug in the stuffer box by means of a pair of photoelectric sensors, which sense the level of the plug and control an electromagnetic clutch to change the drive ratio between the motor and the take up device.

According to a first aspect of the invention there is provided a method of controlling a textile machine for stuffer box crimping of yarns in which yarn is fed to the stuffer box to form a plug of-yarn therein, comprising the steps of withdrawing the yarn from the stuffer box by take up device driven by a D.C. motor, detecting the level of the plug of yarn in the stuffer box, and. so controlling the rotational speed of the D.C. motor in dependence on the detected level of the plug of yarn in the stuffer box that the level of the plug in the stuffer box is maintained within predetermined limits.

According to a second aspect of the invention there is provided a stuffer box crimping machine comprising a stuffer box,'feed means for supplying yarn to the stuffer box to form a plug of yarn therein, a take-up device arranged to withdraw yarn from the stuffer box, a

D.C. motor arranged to drive the take-up device, de-

tector means arranged to produce a level-dependent electrical output in dependence on the level of the plug of yarn in the stuffer box, and control means responsive to the electrical output and operative so to controlthe rotational speed of the D.C. motor, that the plug of yarn in the stuffer box is maintained between predetermined limits in dependence on the said electrical output.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which:

FIG. 1 shows diagramatically a stuffer box crimping machine and associated control system; and

FIG. 2 shows a circuit diagram of the control system illustrated diagramatically in H6. 1.

A textile machine for stuffer box crimping of synthetic filament yarns includes a lower and an upper pair of heated feed rolls 2 and 4 arranged below a pair of crimp wheels 6 of'a stuffer box 8, the feed rolls 2 and 4 and the crimp wheels 6 being driven by a D.C. feed. motor 12.

I The stuffer box is provided with upperand lower detectors l4, 16 which are each operative to detect a' pressure, or absence of a pressure, caused by oscillations of ultra-sonic frequency produced by associated upper and lower emitters l8 and 20 as described in our co-pending British Patent application No. 42l50/71. Detectors of this type may produce a proportional or analogue signal. it will be appreciated however that the detectors may be photoelectric, detectors and'may be operative to detect from associated emitters. The photoelectric detectors may also be arranged to provide a digital signal.

A yarn take-up device indicated generally at 22 includes a spindle 24 mounted on a tilting arm 26, the spindle 24 being driven via drive belts 27 by a D.C. take-up motor 28.

in operation a yarn 30 is wrapped around the upper and lower pairs of heated feed rolls 4 and-2 to be softened, and then passed between the crimping wheel 6 into the stuffer box 8 to form a compact plug 32 of yarn therein. Crimped yarn is withdrawn from the top surface of the plug 32 in the stuffer box 8 and formed into a package 34 on the spindle 24 of the take up device 22.

in FIG. 1 is illustrated schematically a system for controlling the speeds of the feed and take-up motors l2 and 28, and this system includes a control device 36 providing an output signal along a first channel indicated at 38 for controlling the voltage supply to the motor 28 and thereby the rotational speed of the motor 28. The output-signalprovided by the control device 36 is dependent on three signals applied to the input of the control device 36 and on a feed back signal representative of the actual speed of the motor 28.

The first signal, which is dependent on the rate at which yarn 30 is supplied to the stuffer box 8, is supplied along a channel indicated at 42 in the form of a small voltage and is produced by a tachogenerator 39 yarn package 34 formed on the spindle 24. The feed back signal from the motor 28 is supplied along a channel 40 as a voltage from a tachogenerator 37 driven by. the take up motor 28.

- The detectors 14 and 16 are adjusted manually so that they are positioned just above and just below the desired upper and lower levels of the yarn plug in the stuffer box 8. Preferably under operative conditions the height of a plug 32 willbe about 2/3 the height of the stuffer box 8.

When the machine is set into operation the tachogenerator 39 attached to the feed motor 12 supplies the first signal to the control device 36 which signals acts as a reference signal. The second signal from the detectors l8 and 20 of the stuffer box 8 and the third signal from the potentiometer of the diameter sensor 41 are also fed to the control device and the reference signal is modulated by the second and third signals. When the diameter of the'package 34 is at a minimum, little or no modulation of the reference signal is effected by the third signal.

The first, second'and third signals are thus combined to produce the output signal from the control device and the output signal is fed along the channel 38 and is operative to adjust the voltage supplied to the motor 3 and 16 occurs, producing a corresponding corrective change in the output signal and speed of the motor 28 to bring the plug 32 back within the limits.

The feed back signal is fed from the tachogenerator 37 connected to the motor '28, to the control device 36 I and this feed back signal is compared with the output signal to ensure that the motor is rotating at the correct speed determined by the summation of the first, second and third input signals. if the motor is not running at the correct speed the control device 36 acts in a corrective sense to readjust the output signal and thereby the rotational speed of the motor 28.

As the diameter of the package 34 increases the reference signal is increasingly modulated by the third signal from the potentiometer of the diametersensor 41 and the output signal is accordingly adjusted to decrease the rotational speed of the take-up motor 28 and maintain the take-up speed of the yarn from the stuffer the tachogenerator '39 produces a corresponding change in the output signal and in the rotational speed of the D.C. motor 28, causing the take-up device 22 to withdraw yarn from the stuffer box 8 at a correspondingly faster or slower rate. FIG. 2 shows a specific circuit diagram for controlling the speeds of the D.C. feed motor 12 and the D.C.

take-up motor 28.

Referringnow to FIG. 2, the- DLC. feed motor 12 which'has a rating of 4 1-l.P. is controlled by a D.C. drive convertor generally indicated at S0. The D.C. drive convertor 50 comprises-an operational amplifier 51 having its output connected to the gate of a thyristor 53. The anode of the thyristor 53 is connectedto a' main power line 54 and the cathode is connected, by a conductor 55, to the armature 56 of the D.C. feed motor 12. The D.C.drive convertor 50 also includes a bridge rectifier circuit 52 through which a constant voltage is supplied from the main power line 54 to the field winding 57 of the D.C. feed motor. 12.

The output of the tachogenerator 39 driven by. the

'feed motor 12, is connected to a first input of the "operational amplifier 51 and to the input ofa tachofollower 58, and a small control voltage is supplied to a second input of the operational amplifier 51 from a negative volt D.C. supply 59 via a speed control potentiometer 60.

The D.C. take-up motor 28 which has a rating of 1 HP. is controlled by a second D.C. drive convertor generally indicated at 61. The second D.C. convertor 61 comprises an operational amplifier 62 having an output connected to the gate of a thyristor 63, the anode of the thyristor 63 being connected to a main power line 64, and the cathode being connected by a .4 input of the operational amplifier 62 of the convertor 61. I I

The output from the tacho-follower 58 is connected via three serially connected variable resistors 68, 70 and 71 to a second input of the operational amplifier 62 of the convertor 61. The first variable resistor 69 comprises the potentiometer which is operated by the package sensor 41 in response to the detected change in diameter of the package 34; the secondvariable resistor 70 comprises a manually adjustable potentiometer for trimming the mean speed of the take-up motor 28; and the third variable resistor 71 is connected in parallel with a normally closed switch 72 actuated by a relay in response to the upper detector 14. An earth conductor to the armature 66 of the take-up motor 28. The convertor 61 also includes a bridge rectifier circuit 67 via which a constant voltage "is applied to the field winding 68 of the take-up motor 28 from the main power line 64. The output of the tachogeneirator'37 driven bythe take-up motor 28, is connected toafirst justed in a corrective sense to maintain the take up connection via a resistance 73 is provided between the variable resistors 69 and 70.

The signal from the lowerdetector 16 for detecting the lower level of the plug of yarn 32 is fed to a relay actuating a normally open switch 74, and this switch 74 is connected across a variable resistance 75 connected in series between the output of the tachogenerator 37 and the first inputof the operational amplifier 62 of the drive convertor 61.

Suitable values of the various resistances areas folln'operation a constantvoltage is supplied to the field windings 57 and 68 of the feed and take-up motor 12 and 28 from respective main power lines 54 and 64, and voltages are applied to the armatures 56 and 66 of the feed and take up motor 12, 28 via the conductors 55 and 65'from-the respective thyristors 63 and 53 of the drive convertors 50 and 61.

The control voltage applied to the second input of the operational amplifier 51 from the source 59 is manually adjusted by the potentiometer 60 to adjust the output from the amplifier 51, and therefore the voltages supplied by the thyristor 53 to the armature 56 of the feed motor 12, to the desired value requisite with the required rotational speed of the feed motor 12. The output voltage provided by the tachogenerator 39 and representative of the actual speed of the feed motor 12 is fed back, to the first input of the operational amplifier 51 and is compared with the control voltage, and the output from the amplifier 51 is adjusted in a corrective sense to maintain the feed motor 12 rotating at the deand the output of the operational amplifier 62, which is proportional to the reference voltage, controls the thyristor 63 to supply a corresponding voltage to the armature 66 of take up motor 28, and thereby drives the take up motor 28 at a speed dependent on the reference voltage. The output voltage from the tachogenerator 37, which is dependent on the actual rotational speed of the take up motor 28, is fed back to the operational amplifier 62 and compared with the reference voltage, and the output from the amplifier 62 is admotor 28 rotating at the correct speed consistent with the reference voltage. The reference voltage is supplied to the operational amplifier 62 via the variable resistor 69 which is controlled by the diameter sensor 41 to reduce the value of the reference voltage in direct proportion to the increase in diameter of the package, and thereby decrease the speed of the take-up motor 28 as the package diameter 34 increases, and maintain the take-up speed of the yarn constant.

Under normal operation the plug of yarn 32 in-the stuffer box 8 prevents the lower detector 16 from receiving pressure pulses from the lower emitter while the upper detector is able to receive pulses from the upper emitter l8. ln this state the variable resistor 71 is short circuited by the closed switch 72, and the variable resistor 75 is maintained in circuit.

When the height of the plug 32 falls so that the lower detector 16 can receive pulses from the'lower emitter the switch 72 is opened thereby introducingthe variable resistor 71 into the circuit and decreasing the value of the reference voltage sufficiently to produce a gradual 5 percent decrease in the speed of the take-up motor 28. This allows the plug of yarn 32 to build up in the stuffer box- 8.

When the level of the plug 32 rises so that the upper detector 14 isprevented from receiving pulses from the upper emitter 18, the switch 72 is closed thereby shortcircuiting the variable resistor 75. This results in an increase in the feed back-voltage fed to the operational amplifier 62 from the tachogenerator 37 and produces a gradual 5 percent increase in the speed of the take up motor 28, thereby decreasing the level of the plug of yarn 32 in the stuffer box.

These 5 percent adjustments in speed are with respect to the speed which is sustained under normal running that is with the lower detector 16 covered but the upper detector 14 uncovered. This mean speed may be adjusted by means of the potentiometer 69, thus controlling the mean height of the yarn plug 32 between its upper and lower limits.

A textile machine as described above with reference to the accompanying drawings has an advantage over hitherto proposed machines in that much of the mechanical complexity of such proposed machines is avoided by the use of a D.C. motor.

In the above described machine the take-up device is driven directly by the D.C. motor and the operating speed of the take-up device is controlled by controlling ,the voltage applied to the motor. The maximum operat-.

ing speed of the take-up device is then directly dependent on the maximum rotational speed of the motor.

We claim:

1. A stuffer box crimping machine comprising a stuffer box, feed means for supplying yarn to the stuffer box to form a plug of yarn therein, a take-up device arranged to withdraw yarn from the stuffer box and to form the yarn into a package, a D.C. motor arranged to drive the take-up device, detector means arranged to produce a level-dependent electrical output in dependence on the level of the plug of yarn in the stuffer box, a diameter sensor for sensing the diameter of the package and arranged to provide a diameter-dependent electrical output dependent on the diameter of the package, a speed sensor'operative to detect the rate at which yarn is fed to the stuffer box by the feed means and to provide a feed-dependent electrical output in dependence on the detected rate, and control means arranged to receive the level-dependent electrical output, the diameter-dependent electrical output and the a I speed-dependent electrical output and being operative to control the rotational speed of the D.C. motor whereby the plug of yarn in the stuffer box is maintained between predetermined limits in dependence on the said electrical outputs.

2. A machine as claimed in claim 1 further comprising a drive motor for. the feed means, and wherein the speed sensor is a tachogenerator arranged to be driven by the drive motor for the feed means.

3. A machine as claimed in claim 2 wherein the detector means comprises upper and lower detectors arranged at upper and lower levels of the stuffer box and each operative to detect the presence and absence of the plug of yarn at the respective levels, and to provide the level-dependent electrical output, the control means being operative, in response to said leveldependent electrical output, to increase the rotational speed of the D.C. motor when the detected level of the plug of yarn isabove the upper level, being operative to decrease the rotational speed of the DC. motor when the detected level of the plug of yarn is below the lower level, and being operative to maintain the rotational speed of the D.C. motor unchanged when the detected level of the plug of yarn is between the upper and lower levels.

4. A machine as claimed in claim-3 wherein the detectors are ultrasonic wave detectors and wherein the control means includes an amplifier producing an output signal in dependence on a reference signal applied to the input of the amplifier, and wherein the output signal of the amplifier controls a thyristor to supply the voltage to the armature of the D.C. motor whereby to drive the motor at a rotational speed dependent on the reference signal.

5.,A machine as claimed in claim 4 including means for detecting the actual rotational speed of the D.C. motor and providing a feed-back signal dependent on the rotational speed for the amplifier whereby to adjust the amplifier output signal, if necessary, in a corrective sense to maintain the motor rotating at the speed dependent on the reference signal. 

1. A stuffer box crimping machine comprising a stuffer box, feed means for supplying yarn to the stuffer box to form a plug of yarn therein, a take-up device arranged to withdraw yarn from the stuffer box and to form the yarn into a package, a D.C. motor arranged to drive the take-up device, detector means arranged to produce a level-dependent electrical output in dependence on the level of the plug of yarn in the stuffer box, a diameter sensor for sensing the diameter of the package and arranged to provide a diameter-dependent electrical output dependent on the diameter of the package, a speed sensor operative to detect the rate at which yarn is fed to the stuffer box by the feed means and to provide a feed-dependent electrical output in dependence on the detected rate, and control means arranged to receive the level-dependent electrical output, the diameter-dependent electrical output and the speed-dependent electrical output and being operative to control the rotational speed of the D.C. motor whereby the plug of yarn in the stuffer box is maintained between predetermined limits in dependence on the said electrical outputs.
 2. A machine as claimed in claim 1 further comprising a drive motor for the feed means, and wherein the speed sensor is a tachogenerator arranged to be driven by the drive motor for the feed means.
 3. A machine as claimed in claim 2 wherein the detector means comprises upper and lower detectors arranged at upper and lower levels of the stuffer box and each operative to detect the presence and absence of the plug of yarn at the respective levels, and to provide the level-dependent electrical output, the control means being operative, in response to said level-dependent electrical output, to increase the rotational speed of the D.C. motor when the detected level of the plug of yarn is above the upper level, being operative to decrease the rotational speed of the D.C. motor when the detected level of the plug of yarn is below the lower level, and being operative to maintain the rotational speed of the D.C. motor unchanged when the detected level of the plug of yarn is between the upper and loweR levels.
 4. A machine as claimed in claim 3 wherein the detectors are ultrasonic wave detectors and wherein the control means includes an amplifier producing an output signal in dependence on a reference signal applied to the input of the amplifier, and wherein the output signal of the amplifier controls a thyristor to supply the voltage to the armature of the D.C. motor whereby to drive the motor at a rotational speed dependent on the reference signal.
 5. A machine as claimed in claim 4 including means for detecting the actual rotational speed of the D.C. motor and providing a feed-back signal dependent on the rotational speed for the amplifier whereby to adjust the amplifier output signal, if necessary, in a corrective sense to maintain the motor rotating at the speed dependent on the reference signal. 